add socket snippet

Socket_snippet/server.c

@@ -0,0 +1,150 @@
+/*
+ * This file is part of the socksnippet project.
+ * Copyright 2022 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <netdb.h>
+#include <poll.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <usefull_macros.h>
+
+#include "server.h"
+#include "socket.h"
+
+// server-side functions
+
+// command handlers
+hresult pinghandler(int fd, _U_ const char *key, _U_ const char *val){
+    sendstrmessage(fd, "PING");
+    return RESULT_SILENCE;
+}
+
+static int sendtime = 0;
+hresult timehandler(_U_ int fd, _U_ const char *key, _U_ const char *val){
+    sendtime = 1;
+    return RESULT_OK;
+}
+
+static int value1 = 0, value2 = 0;
+hresult valsethandler(_U_ int fd, const char *key, const char *val){
+    if(!val || !*val) return RESULT_BADVAL;
+    int i = atoi(val);
+    if(i < -65535 || i > 65535) return RESULT_BADVAL;
+    if(strcmp(key, "setval1") == 0) value1 = i;
+    else value2 = i;
+    return RESULT_OK;
+}
+hresult valgethandler(int fd, const char *key, _U_ const char *val){
+    char buf[32];
+    if(strcmp(key, "getval1") == 0) snprintf(buf, 32, "VAL1=%d", value1);
+    else snprintf(buf, 32, "VAL2=%d", value2);
+    sendstrmessage(fd, buf);
+    return RESULT_SILENCE;
+}
+
+/*
+hresult handler(_U_ int fd, _U_ const char *key, _U_ const char *val){
+    ;
+}
+*/
+
+static handleritem items[] = {
+    {pinghandler, "ping"},
+    {timehandler, "time"},
+    {valsethandler, "setval1"},
+    {valsethandler, "setval2"},
+    {valgethandler, "getval1"},
+    {valgethandler, "getval2"},
+    {NULL, NULL},
+};
+
+/**
+ * @brief processData - process here some actions and make messages for all clients
+ * @param buf (o) - buffer for answer
+ * @param l - max length of buf
+ * @return amount of answer bytes
+ */
+static int process_data(char *buf, int l){
+    if(!buf || !l) return 0;
+    /* USERCODE: get here some data to send all clients */
+    if(sendtime){
+        snprintf(buf, l, "TIME=%.2f", dtime());
+        sendtime = 0;
+        return strlen(buf);
+    }
+    return 0;
+}
+
+#define CLBUFSZ     BUFSIZ
+
+void server(int sock){
+    if(listen(sock, MAXCLIENTS) == -1){
+        WARN("listen");
+        LOGWARN("listen");
+        return;
+    }
+    int nfd = 1; // only one socket @start
+    struct pollfd poll_set[MAXCLIENTS+1];
+    char buffers[MAXCLIENTS][CLBUFSZ]; // buffers for data reading
+    bzero(poll_set, sizeof(poll_set));
+    // ZERO - listening server socket
+    poll_set[0].fd = sock;
+    poll_set[0].events = POLLIN;
+    while(1){
+        poll(poll_set, nfd, 1); // max timeout - 1ms
+        if(poll_set[0].revents & POLLIN){ // check main for accept()
+            struct sockaddr_in addr;
+            socklen_t len = sizeof(addr);
+            int client = accept(sock, (struct sockaddr*)&addr, &len);
+            DBG("New connection");
+            LOGMSG("SERVER got connection, fd=%d", client);
+            if(nfd == MAXCLIENTS + 1){
+                LOGWARN("Max amount of connections, disconnect fd=%d", client);
+                WARNX("Limit of connections reached");
+                close(client);
+            }else{
+                memset(&poll_set[nfd], 0, sizeof(struct pollfd));
+                poll_set[nfd].fd = client;
+                poll_set[nfd].events = POLLIN;
+                ++nfd;
+            }
+        }
+        char buff[BUFLEN];
+        int l = 0;
+        // process some data & send messages to ALL
+        if((l = process_data(buff, BUFLEN-1))){
+            DBG("Send to %d clients", nfd - 1);
+            for(int i = 1; i < nfd; ++i)
+                sendmessage(poll_set[i].fd, buff, l);
+        }
+        // scan connections
+        for(int fdidx = 1; fdidx < nfd; ++fdidx){
+            if((poll_set[fdidx].revents & POLLIN) == 0) continue;
+            int fd = poll_set[fdidx].fd;
+            if(!processData(fd, items, buffers[fdidx-1], CLBUFSZ)){ // socket closed
+                DBG("Client fd=%d disconnected", fd);
+                LOGMSG("SERVER client fd=%d disconnected", fd);
+                buffers[fdidx-1][0] = 0; // clear rest of data in buffer
+                close(fd);
+                // move last FD to current position
+                poll_set[fdidx] = poll_set[nfd - 1];
+                --nfd;
+            }
+        }
+    }
+}